Patent GB-421568-A (GB)
Title: Improvements in and relating to grinding or abrading machines
IPC: B24B49/04
Filed: 1933-05-18
Abstract: 421,568. Grinding-machines. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.- (Norton Co. ; New Bond Street, Worcester, Massachusetts, U.S.A.) May 18, 1933, No. 14397. [Class 60] A cylindrical grinding-machine is provided with gauging means comprising a feeler which engages the work until this has reached a predetermined size, when the feed of the grinding- wheel is stopped and, after the work has reached another predetermined size, is withdrawn from the work the final grinding being performed for a predetermined time with the feeler removed. Movement of the gauge up to and away from the work also automatically starts and stops the rotation of the work, the supply of cooling fluid, and the feeding cycle of the grinding- wheel. The machine comprises a base 20 carrying a longitudinally movable work-table 21 and a grinding-wheel 23 on a. slide 24 movable up to and away from the work. Feeding mechanism. The slide 24 may be fed manually by a hand wheel 33, operating, through gears 27, 28, 30, 31 a feed screw 26, or by power from a shaft 35. The shaft 35 drives, through worm gearing 36, 37 and a pinion 39, a tumbler gear 42 carried by a frame 43 pivoted on the shaft 38 of gear 39 and moved by a lever 44 to carry the gear 42 into mesh with a gear 30 on the shaft 29 of the gear 28, to give the wheel slide 24 a feeding movement, to disengage the gears to stop the feed, or to bring another gear 48 on the frame into operation to reverse the movement of the slide 24 ; the lever occupies the positions 44, 44a, 44b, respectively to give the above three operations. Headstock mechanism. The work is supported on a footstock centre and on a headstock centre 51, and is driven from a pulley 58 through a clutch 59 operated by a solenoid 62. Cooling Fluid system. Cooling fluid is supplied to the work by a pump through a pipe 70, valve 71, pipe 72, manually operated valve 73 and spout 74, the valve 71 being opened by a spring 75 and closed by a solenoid 76. Calipering or sizing head. The work is gauged by means of a device comprising a head 80 carrying work engaging screws 82, 83 and a slidable feeler 84 engaging a micrometer screw 85 on a bell - crank lever 86 pivoted' by a knife edge 87 resting in a support on the head 80. A short arm 90 of the lever has thereon a contact 91 to engage a contact 92 adjustable by a screw 94, and a long arm 95 of the lever carries a contact 96 to engage a contact 97 adjustable by a screw 99. The head is carried by a shaft 104 mounted in a bracket 103 on a part 102 carried by the wheel guard 100, and the head has thereon a bracket 106 pivotally connected to a rod 107 mounted in a bracket 108 pivoted on the shaft 104, to which also is connected one end of a clock spring 109 of which the other end is fixed to a stud on the bracket, tending to lift the head 80 to an inoperative position ; when the head is swung down, a groove 114 therein engages a pin 115 on a slide block 116 movable within a curved slideway 117. Timing control. In order to give a rough grinding operation, followed by a finishing operation for a predetermined interval, a time-delay device is provided comprising a dash-pot cylinder 120 carried in a housing 121 on the shaft 104 and having therein a piston 122 connected to a cross arm 124 and urged downwards by a spring 125 in an upper chamber 126. Below the piston is oil, which by downward movement is forced through an adjustable needle valve 129 into chamber 126, valves 130 in the piston facilitating the return upwards of the piston. The arm 124 is connected by a link 135 to a stud on a rock arm 137, mounted on the shaft 104 and connected by a link 138 to the slide 116. The piston is held lifted by a pawl 145 moved to engage the arm 124 by a spring 149 and tripped by a solenoid 150. The rod 107 is connected to a link 155 having therein a slot 157 so that as the head 80 is swung down the arm 124 at first is not moved, and then is moved to engage the pawl to locate the piston correctly in the cylinder. Automatic control, work rotation and cooling fluid. In order that, as the head is rocked to engage the work, the rotation of the work may be started, the cooling fluid turned on, and the infeed started, the arm 137 carries an arm 160 on which is a contact member 161, which engages contacts 162-165 arranged in pairs 162, 163 and 164, 165 separately adjustable, the arm 137 being moved from the arm 124 by a link 135, the contacts 164, 165 first and then the contacts 162, 163 being engaged by the member 161. Electrical control. The contact points of the machine are situated in low voltage relays serving to make and break higher voltage circuits operating the various solenoids. The arm 44 is swung into its three positions respectively by solenoids 180, 184, 188 and to limit the movement of the grinding-wheel away from the work, two contacts 206, 205 are provided on the frame 20 adapted to be engaged by a disc 207 on a shaft 208 carrying an adjustable stop engaged and moved rearwards, against the action of a spring, by a stop 209 on the wheel slide 24. Relays 195-198 are provided having adjustable contacts, the relays 198, 195 also having fixed contacts 232, 242 respectively. The magnets of the relays are connected direct to one terminal of a battery 194 and through the various contacts to the other terminal, whilst a source of high voltage has one terminal 192 connected direct to the movable contact arm of the relays, and the other terminal 193 connected through the various solenoids to the fixed contacts of the relays. Operation. A work-piece is mounted on the machine centres, and the head 80 swung manually towards the work. During this movement, the contacts 164, 165 are closed to start work rotation and flow of cooling fluid, and further movement causes initiation of the feed movement of the grinder by rocking of the arm 43 ; the pawl 145 also locks the dashpot cylinder in position. Infeed continues to rough grind the work until the feeler 84 moves sufficiently to break the contact 92 ; this stops the feed. The grinding-wheel then remains in contact with the work to finish grind, without feed until the feeler 84 moves sufficiently to break the contact 97 ; this releases the pawl 145 and causes, firstly, the withdrawal of the feeler 84 and associated parts from the work by the action of the spring 125 on the piston 122, and then withdrawal of the grinding-wheel from the work, giving sufficient time for the wheel to grind to remove the marks made by the feeler before all of the movements are stopped by the head 80 reaching its inoperative position.. Specification 363,695 is referred to.